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金属卟啉配合物作为主体分子对氨基酸酯及其衍生物的分子识别研究是当今卟啉仿生化学的重要课题[1-6]。这一领域的研究成果在生物传感器的研制,癌症的诊断和治疗,模拟含卟啉生物大分子的功能以及在生物大分子构象和类型的识别研究中具有潜在的应用价值[7]。氨基酸是弱的电子授体,将其连接在卟啉分子中可以改变卟啉配体的受授性质,同时氨基酸尾式卟啉更接近天然卟啉。另外,氨基酸是蛋白质的主要组成部分,在蛋白质的生物合成过程中,对氨基酸及其衍生物的识别是关键的一步。酰胺转移t-RNA合成酶对氨基酸表现出极为专一的立… 相似文献
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氨基酸、多肽的环糊精化学 总被引:7,自引:0,他引:7
本文着重介绍了氨基酸、多肽-环糊精连接物的合成,分子识别和自组装,对环糊精及其衍生物与氨基酸、多肽的包合行为,异构体识别和仿酶合成作了简要概述。 相似文献
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本文用分光光度滴定法测定了单-[6-(1-吡啶)-6-脱氧]-α-和γ-环糊精(1)和(3)与一系列氨基酸在磷酸缓冲溶液中(pH=7.20),25.0~40.0℃时形成超分子体系的稳定常数,进而计算了配位焓和配位熵,并与单-[6-(1-吡啶)-6-脱氧]-β-环糊精(2)的实验结果作了比较.化学计量法表明,所有的氨基酸均与环糊精衍生物形成了1:1的超分子体系.从热力学的观点,讨论了化学修饰环糊精和客体氨基酸的尺寸或形状适合、疏水效应、范德华力和氢键等几种弱相互作用力对形成超分子体系的贡献.研究结果发现,具有正电荷环糊精衍生物的吡啶基,作为一种分子探针不仅可以识别氨基酸生物分子的尺寸或形状之间的差异,而且还可以识别L/D-型手性对映体之间的差异,进一步表明了主-客体间的诱导楔合、几何互补在分子受体选择性键合底物形成超分子体系中的重要作用. 相似文献
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确定蛋白质-短肽复合物结构的新方法 总被引:1,自引:1,他引:0
大部分蛋白质 -蛋白质复合物的三维结构在接触表面都显示出很好的几何匹配 .由于蛋白质的表面几何形状和其它的一些物理化学性质在分子的专一性相互作用中起了主要作用 ,所以 ,接触表面几何形状的互补常常被认为是蛋白质分子识别的基础 .一般来说 ,蛋白质接触表面的几何匹配只涉及 5到 1 0几个紧密堆积的氨基酸残基 ,因此 ,蛋白质与蛋白质配体之间的识别计算可以通过蛋白质与突变周围的或与蛋白质表面紧密接触的配体肽段的识别计算来实现 . Stoddard等 [1] 已经利用从 MBP上选取的八肽成功地计算出接近晶体结构的 MBP-受体复合物 .许多研… 相似文献
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蛋白质是各种生物形态结构和生命活动所依赖的物质基础,在水溶液中蛋白质天然结构的稳定性归结于氨基酸残基之间以及与溶液中其它组分的相互作用.天然环境中存在的众多物质对蛋白质的溶解度、变性行为和解缔等都有很大的影响.为深入了解蛋白质折叠与解折叠过程中的物理化学现象,以氨基酸、肽、酰胺及其衍生物作为蛋白质模型分子的热力学研究引起了广泛重视. 相似文献
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对叔丁基硫杂杯四酰肼衍生物(2)与邻苯二甲醛发生分子内1+2缩合反应, 合成了首例1,3-交替构象的硫杂杯-1,3-2,4-氮杂双冠醚(3), 产率为65%. 其结构经元素分析、质谱、核磁共振谱等表征证实. 用UV-Vis光谱法和1H NMR谱研究了化合物3与系列α-氨基酸的识别配合性能, 并计算出其配合常数. 结果表明, 主体分子3对所测试的α-氨基酸有较好的配合作用, 主客体分子形成1∶1的配合物. 相似文献
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超分子体系中的分子识别研究 5: 单-[6-(1-吡啶)-6-脱氧]-α-和γ-环糊精对氨基酸分子识别的热力学性质 总被引:3,自引:0,他引:3
本文用分光光度滴定法测定了单-[6-(1-吡啶)-6-脱氧]-α-和γ-环糊精(1)和(3)与一系列氨基酸在磷酸缓冲溶液中(pH=7.20), 25.0~40.0℃时形成超分子体系的稳定常数, 进而计算了配位焓和配位熵, 并与单-[6-(1-吡啶)-6-脱氧]-β-环糊精(2)的实验结果作了比较。化学计量法表明,所有的氨基酸均与环糊精衍生物形成了1:1的超分子体系。从热力学的观点,讨论了化学修饰环糊精和客体氨基酸的尺寸或形状适合、疏水效应、范德华力和氢键等几种弱相互作用对形成超分子体系的贡献。研究结果发现, 具有正电荷环糊精衍生物的吡啶基, 作为一种分子探针不仅可以识别氨基酸生物分子的尺寸或形状之间的差异, 而且还可以识别L/D-型手性对映体之间的差异, 进一步表明了主-客体间的诱导楔合、几何互补在分子受体选择性键合底物形成超分子体系中的重要作用。 相似文献
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本文合成了含有单取代酰胺基的不对称卟啉及其锌(Ⅱ)络合物Zn(m,2-CNTPP)及Zn(m,3-CNTPP).对三氯甲烷溶液中它们与谷氨酸二甲酯、亮氨酸甲酯以及苯丙氨酸甲酯的作用进行了系统的研究,讨论了卟啉化合物对氨基酸甲酯分子的结合能力、结合方式,以及二者之间的多种存在形式。结果表明,锌卟啉与氨基酸甲酯以1:1的化学计量结合,中心金属锌(Ⅱ)离子和氨基酸甲酯中的氨基配位,卟啉环上的取代基与氨基酸甲酯中的残基可形成氢键、范德华力等弱相互作用。在卟啉和氨基酸甲酯的作用中,氨基与金属离子直接配位,α-碳上的质子靠近卟啉环平面,而酯基中的甲氧基处于远离卟啉环平面的位置。 相似文献
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以新手性拆分试剂R(-)四氢噻唑-2-硫酮-4-羧酸[简称R(-)TTCA]对D,L-氨基酸酯进行手性拆分,分别得到(R)TTCA氨基酸酯盐1a_1f([α]D20=-30.40°~-42.70°)及光学活性氨基酸酯2a-2f,其光学纯度为35.4%~75.8%.由1a_1f在碱存在下分解出2a-2f的对映体3a-3f,光学纯度为39.50%~69.10%.用半经验的量子化学PM3方法研究了氨基的碱性、中间产物铵盐生成热和稳定性. 相似文献
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A. V. Lebedev A. B. Lebedeva V. D. Sheludyakov V. V. Shatunov S. N. Ovcharuk 《Russian Journal of General Chemistry》2007,77(4):581-585
Treatment of an alcoholic suspension of amino acids with trimethylchlorosilane yielded phenylglycine, valine, β-phenylalanine, and homovaline ester hydrochlorides. Their saccharin-catalyzed silylation with hexamethyldisilazane proceeds quantitatively and involves only one proton of the amino group. The best conversion of the amino acid esters to the corresponding isocyanates was achieved by phosgene treatment of their monosilyl urethanes, rather than of the silylated amino esters. Monosilyl urethanes are formed quantitatively by treatment of the amino acid ester hydrochlorides with the hexamethyldisilazane-CO2 system. The 1H NMR spectra show that monosilyl urethanes derived from α-and β-amino acid esters are characterized by intramolecular interaction of the silicon atom and the oxygen atom of the carboxy group. 相似文献
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The solvent effect on acetyl amino acid methyl esters and C- and N-protected di- and tripeptide derivatives has been studied in deuterium oxide (D2O), 1.1.1.3.3.3-hexafluoroisopropanol (HFiP), dimethyl sulfoxide (DMSO) and methylene chloride (CH2Cl2). The interpretation is based on the amide I region. For the amino acid derivatives the relative shift of the amide I signal clearly indicates the strength of the interaction with the solvent molecules. However, in HFiP and DMSO solutions the occurrence of two overlapping signals for the amide I and the ester carbonyl signal, respectively, indicates the existence of two major conformers. Knowing the solvent effects on the small amino acid esters allows the assignment of the signals in di- and tripeptide derivatives. Although the identification of turn structures in these flexible molecules is not possible, the band positions and intensity of the deconvoluted amide I region clearly shows that certain conformers can be stabilised. It can be concluded that the band profile in the amide I region is determined by the number of amino acid residues linked in the molecule, the bulkiness of the side chains and their sequence and to a major extend by the solvent properties. 相似文献
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Mary E. Neubert Sandra S. Keast Catherine C. Law Mark C. Lohman Jay C. Bhatt 《Liquid crystals》2005,32(6):781-795
A variety of 4,4'-disubstituted phenyl benzoates having a terminal chain containing multifluorine atoms, attached directly to the benzene ring or through an ester group, have been synthesized and their mesomorphic properties determined by hot stage polarizing optical microscopy. These properties were compared to those of the corresponding hydrogenated esters and to other esters containing rigid terminal chains. Usually transition temperatures were higher and mesophase ranges wider than those observed for the parent compounds but no nematic phases were found. Any mesophase seen was usually a smectic A phase sometimes accompanied by a smectic C phase. Crystal E phases were found along with the smectic A phase in alkyl or alkoxy esters having a C9F19CO2 chain on the acid side. A first order smectic A-smectic C transition was observed in the ester with CN on the acid side and O2CC7F15 on the phenol side. A comparison of the effect of a terminal fluorinated chain and a lateral fluorine group on one set of esters is also included. 相似文献
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SANTIAGO NONELL MARÍA L. SESÉ DANIEL O. MÁRTIRE SILVIA E. BRASLAVSKY FRANCESC R. TRULL † 《Photochemistry and photobiology》1991,53(2):185-193
Abstract— Several porphyrin esters used as models for polystyrene-bound porphyrins have been prepared and their excited states have been studied by laser flash photolysis, IR phosphorescence of singlet molecular oxygen, O2 (1 Δg ), and steady-state fluorescence. The photophysical properties of the porphyrin esters in solution are affected by the presence of nitro group(s) in the chain. In this case, an important decrease in φf , φT and φδ (to ca 0.7–0.4 of the value for the parent dimethyl ester) is observed. This is mainly due to intramolecular electron-transfer quenching [by the nitro group(s)] of the first excited singlet state of the porphyrin. The thermodynamic feasibility of this deactivation pathway has been confirmed polarographically. Quenching of the porphyrin triplet state and of O2 (1 Δg ) by the nitro groups is negligible. The present conclusions explain also the results obtained previously for the photooxidation of bilirubin sensitized by the parent insoluble polystyrene-bound porphyrins. In that case the photooxidation rates were correlated directly with the quantum yield of O2 (1 Δg ) production by the sensitizer. The consequences of these results for the use of polystyrene-bound porphyrins in sensitized photooxidation processes are discussed. 相似文献
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Serra VV Domingues MR Faustino MA Domingues P Tomé JP Neves MG Tomé AC Cavaleiro JA Ferrer-Correia AJ 《Rapid communications in mass spectrometry : RCM》2005,19(18):2569-2580
Porphyrin amino acid conjugates with one or two porphyrin units were analyzed by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The ESI-MS spectra of all the porphyrins studied, obtained in positive ion mode, show the presence of the corresponding protonated molecule [M+H]+; ESI-MS spectra of diporphyrinyl compounds also show the doubly charged ions [M+2H]2+. The fragmentations of these ions induced by collision with argon were studied (ESI-MS/MS). ESI-MS/MS gives detailed structural information about the amino acids associated with the porphyrin. Cleavage of the bonds in the vicinity of the porphyrin moiety and those involving the side chain of amino acid residues gives structural information about this type of association. A fragmentation common to all derivatives corresponds to the cleavage of the phenyl-CO bond. The expected cleavage of the amide bond, that links the porphyrin to the amino acid moiety, is a minor fragmentation, which in some cases is even absent. The MS/MS spectra of the monoporphyrinyl derivatives show product ions characteristic of the amino acid linked to the porphyrin; the fragmentation also indicates when the amino acids has a terminal carboxylic group or a terminal ester group. The fragmentations of the diporphyrinyl compounds occur mainly by the cleavage of the spacer, leading, in the case of the doubly charged ions, to predominantly mono-charged ions, indicating a preferential location of the two protons in separated porphyrinic units. 相似文献
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含双蒽基团酰胺受体分子的合成及阴离子识别研究 总被引:5,自引:0,他引:5
合成了一种新型的带有双蒽基团的酰胺阴离子受体B.用荧光光谱、紫外-可见吸收光谱以及核磁共振氢谱研究了B与Cl-,Br-,I-及对硝基酚氧阴离子的相互作用.结果表明,B与Cl-,Br-,I-等阴离子无识别作用,而与对硝基酚氧阴离子有较好的选择性识别能力,其络合比为1∶1.利用荧光发射强度和吸光度的变化分别计算出主体B与客体相互作用的络合常数KS分别为(1.24±0.07)×105和(1.27±0.18)×105,并对主体分子B与客体之间的相互作用进行了讨论. 相似文献